Many important discoveries in the field of developmental biology have come from studies of amphibian embryos. Because they are large and sturdy, they can be readily manipulated and injected. The limitations to these types of studies derive from the fact that morphology alone is used as the criterion for dissection. In addition, Xenopus laevis is not a model genetic organism. Its generation time is long, and its genome is tetraploid. The Russian and US investigators propose to unite technologies independently developed to address these limitations of the laevis system. Dr. Zairisky's group has developed several new fluorescent proteins (FPs), which can be used to mark cells. Dr. Grainger's group has initiated amphibian studies in the genetically tractable animal (it's diploid and has a short generation time) Xenopus tropicalis. The objective of the current research proposal is technological (to construct transgenic animals in which the new fluorescent proteins are expressed under different promoters) and biological (to study how the anterior part of the brain is formed).